Method for Producing Lump Semicoke

ABSTRACT

The invention relates to producing lump semicoke and can be used in metallurgy. Essence of the invention consists in that a method for producing said lump semicoke calls for using, as coal bed, coal having a fraction of 20-70 mm and air is supplied thru the coal bed with a relative blowing rate of 70-99.5 m 3 /m 2 ·hr according to a coal rank.

FIELD OF THE INVENTION

The invention is related to a field of producing lump semicoke and can be used in metallurgy.

BACKGROUND OF THE INVENTION

Known is a method for producing lump semicoke by distillation of solid carbon-containing raw materials in a vertical autothermal apparatus of the shaft type using blast furnace air comprising heating, drying and carbonating said raw material, discharging the semicoke so produced from below and the withdrawal of fuel gas, said blast furnace air is added with a product fuel gas having the exit temperature of the apparatus in the concentration not exceeding the lower limit of gas inflammation with about 8-10% of the gas added to said blast furnace air of the volume of the fuel gas thus produced with a carbonization temperature of between 920 and 950° C. while said blast furnace air is provided from the side opposite coal kindling with a blast intensity of 100-400 m³/m²·hr (RU 2169166 C1).

The closest to the claimed method as to the result being obtained and technical essence is a method for producing a carbon adsorbent in a vertical apparatus of the shaft type with internal heating-up by burning the volatile matter and a portion of the carbon residue in a coal bed blown by an air flow (RU 2014883). The method calls for firing the coal bed from the side opposite blast furnace air supply. A combustion front is shifted toward the air flow and a solid residue is left behind the front containing the carbon that has not been burned out. With movement of the combustion front, the coal bed is passed in succession thru the steps of heating, drying and carbonization. A gas-vapor mixture of carbonization products and a portion of the solid carbon residue are reacted with atmospheric oxygen until it is completely exhausted to create a combustion front with a temperature of from 750 to 900° C., with a zone of reducing combustion products formed behind the combustion front (CO₂ and H₂O) up to a carbon/hydrogen oxide. The fuel gas is withdrawn from the apparatus for the subsequent treatment and use. And the solid residue has high internal porosity (above 60%) that provides a high sorption activity of the product and its subsequent use as adsorbent.

The disadvantages of said method are as follows:

Despite closeness to lump semicoke as to a chemical composition, the product being produced has a limited field of use in metallurgy because of an increased content of tiny fractions, low density and increased ash content. High porosity much reduces the strength of a carbon residue. A disadvantage is also a decreased specific output of solid product due to a substantial combustion loss of starting carbon-containing raw materials.

SUMMARY OF THE INVENTION

The invention solves the task of raising the quality of the solid product so obtained that meets the requirements imposed on lump semicoke.

The technical result resides in, at the time of using the invention, obtaining a solid product having higher strength and density, a low ash content and also a bigger average size of a lump and in increasing the specific output of the solid product.

Said technical result is achieved owing to the fact that a coal bed is represented by the coal having fractions of 20 to 70 mm and air is supplied thru said coal bed with a relative blowing rate of 70-99.5 m³/m²·hr, according to a coal rank.

DETAILED DESCRIPTION

A method for producing lump semicoke is carried out in the following manner.

A vertical shaft-type apparatus is charged by overall height with crushed coal having fractions of 20-70 mm, blast furnace air is supplied with a relative blowing rate of 70 to 99.5 m³/m²·hr (according to a coal rank, kindling a coal bed from the side opposite blast supply. The formable front of carbonization is shifted at constant speed toward an air flow and a hot semicoke bed remains behind the front. On passage thru the front of carbonization, the coal is gradually passed thru the steps of heating, drying and pyrolysis. The combustible components of pyrolysis products burn up completely in atmospheric oxygen to form carbon dioxide and a water steam and then transform by reduction on the hot surface of said semicoke into the combustible components of gas (carbon oxide and hydrogen) that is devoid of the pyrolysis products. On reaching a bed side by the front of carbonization, which is opposite a firing side, the process is completed. The semicoke bed is cooled and discharged from a lower side of the vertical apparatus.

In the examples illustrating a method, use is made of a vertical shaft-type apparatus having a root dia. of 0.5 m and a height of 1.5 m.

EXAMPLE 1

Raw material is coal having fraction of 20 to 60 mm (Shoubarkol coal, rank D, Kazakhstan) having the following technical and elemental composition:

W^(r) _(t) = 12.2% C^(daf) = 77.9% A^(d) = 2.4% H^(daf) = 5.3% V^(daf) = 44% N^(daf) = 1.2% Q^(r) _(t) = 25.7 MJ/kg Q^(daf) = 15/16% S^(daf) = 0.44%

Some 160 kg of crushed coal are charged into an apparatus. A bed is fired from top. Blast furnace air is supplied from below. On reaching a lower side of coal by a combustion front, the process is completed.

Relative blowing rate 99.5 m³/m² · hr Movement speed of 11.5 cm/hr combustion front Semicoke specific output 42.4 kg/m² · hr Output of semicoke 48.6% Output of fuel gas 165 m³/m² · hr Latent heat of raw gas 2.4 MJ/m³ combustion Semicoke ash content A = 5.4% Semicoke apparent density 0.68 g/m³ Semicoke structural strength 74.8% Semicoke granulometric over 20 mm - 25% 10-20 mm - 58% composition 5-10 mm - 11% less than 5 mm - 6%

EXAMPLE 2

Raw material is coal having fraction of 10 to 60 mm (Berezovsk, rank

, Kansko-Achinsk basin) having the following technical and elemental composition:

W^(r) _(t) = 10% C^(daf) = 71% A^(d) = 7% H^(daf) = 5.1% V^(daf) = 48% N^(daf) = 0.7% Q^(r) = 22.08 MJ/kg Q^(daf) = 22.3% S^(daf) = 0.3%

Some 123 kg of crushed coal are charged into an apparatus. A bed is kindled from top. Blast furnace air is supplied from below. On reaching a lower side of a coal bed by a combustion front, the process is completed.

Relative blowing rate 76.4 m³/m² · hr Movement speed of 9.2 cm/hr combustion front Semicoke specific output 27.7 kg/m² · hr Output of semicoke 43% Output of fuel gas 100.2 m³/m² · hr Latent heat of raw gas 2.32 MJ/m³ combustion Semicoke ash content A = 15% Semicoke density 0.45 g/m³ Semicoke strength 60%% Semicoke granulometric 5-10 mm - 21.5% less than 5 mm - 78.5% composition

EXAMPLE 3 Comparative

Some 135 kg of coal having a fraction of 5-20 mm, rank

(Borodino coal) are charged into an apparatus. Technical and elemental composition:

W^(r) _(t) = 30% C^(daf) = 71% A^(d) = 90% H^(daf) = 5% V^(daf) = 22.5% N^(daf) = 1% S^(daf) = 0.5%

Blast furnace air is supplied from below at a discharge rate of 35 m³/hr; coal is kindled from top. In eight hours, a combustion front reaches the level of air supply and the apparatus is discharged. The output of an adsorbent was 37 kg or 27.4% of starting coal.

Parameters thereof: humidity 0.5%, ash content 21-28%, bulk density 0.45 g/cm³, abrasion resistance (GOST 16188-70) 85-86%, total pore volume 0.6 cm³/g, specific pore surface 850 m²/g, adsorption activity in terms of iodine (GOST 6217-74)-68.6% and methylene blue (GOST 6217-74) 28-60 mg/g.

Thus, the claimed method allows one to obtain a solid product having higher strength and density, a low ash content and also a larger average size of a lump and to increase a specific output of the solid product (cf. Table).

TABLE Example 3 Example 1 Example 2 (comparative) Coal fraction size, mm 20-60 20-60  5-20 Relative blowing rate 99.5 76.4 100-400 m³/m²hr Ash content A^(d), % 5.4 15 21-28 Structural strength 74.8 60 — semicoke, % Apparent density, 0.68 0.45 — semicoke g/m³ Solid product, output 48.6 43 27.4 

1. A method for producing lump semicoke comprising the thermal treatment of a coal bed in a vertical shaft-type apparatus on kindling from the side opposite air supply, characterized in that the coal bed used is represented by coal having a fraction of 20-70 mm and air is supplied thru the coal bed with a relative blowing rate of 70-99.5 m³/m²·hr, in relation to a coal rank. 